It's cool I guess I'm miss understanding then. Both of my cars have plastic reservoirs and are under pressure, of course they're both German so that might have something to do with it.
It doesn't matter look at the giant ! on the reservoir. Releasing pressure on the system will all have the same result. Take a physics or chemistry class.
Those are your rod end caps, not your main bearing cap. The main bearing caps hold on your crankshaft, not your pistons. But, I guess the lower case works as the cap also.
Crazy indeed. A bird doesn't need to be going a hundred mph to generate enough lift to fly. Just like an airplane, if the giant flying squirrel guy isn't going fast enough he'll fall out of the sky like a stone, then SPLAT!! human marmalade.